1. Field of the Invention
This application relates to methods and apparatus for providing services to subscribers in a telecommunications network. In particular, but not exclusively, this application relates to the delivery of advanced telephony services for calls received on local telephone exchange switches.
2. Description of the Related Technology
Local telephone exchange switches deliver telephony services to residential and business customers, including a variety of functions that enable such customers to control the behavior of incoming and outgoing telephone calls; for example, call forwarding services, whereby the customer can request that calls to their telephone number be diverted to some other telephone number.
Some users of telephony services desire more sophisticated control over the behavior of telephone calls than is commonly provided by the majority of local telephone exchange switches that are deployed in the Public Switched Telephone Network (PSTN). An established technique for the delivery of such advanced telephony services is to make use of a capability that is offered by some local telephone exchange switches known as Advanced Intelligent Network (AIN). By means of AIN, calls to specific numbers served by the local telephone exchange switch can trigger a query that is sent to an external computing system, and the response provided by this computing system can be interpreted by the local telephone exchange switch so as to determine how to treat the call. Commonly, the call is re-directed to another system which provides the means to play announcements, collect digits dialed by the caller, re-direct the call to the originally-called number or to some other destination, release the call, etc.
FIG. 1 is a diagram showing a telecommunications network according to the prior art. FIG. 1 shows a common channel signaling network operating according to the Signaling System 7, which is commonly referred to as an SS7 network. Such an SS7 network separates the media path by which voice media, i.e. the voice payload for telephone calls, from the signaling path by which signaling information such as call setup information passes. In FIG. 1, voice media for a telephone call conducted between telephones 100 and 102, passes through telephone switches 104 and 106, whilst the signaling information passes from switch 104 to signaling transfer points 108 and 110 to switch 106, rather than along the media path between switches 104 and 106. FIG. 1 shows switches 104 and 106 connecting the call between telephones 100 and 102 across the network, although in reality more switches (not shown) may be involved. FIG. 1 shows signaling transfer points (STPs) 108 and 110 transferring the necessary signaling information for the telephone call across the network, although in reality more STPs (not shown) may be involved. Although freeing up connections between switches for the flow of call media data compared to previous network configurations, a basic SS7 network has limited capabilities in terms of providing advanced telephony services.
FIG. 2 is a diagram showing a telecommunications network according to the prior art. In this network, an advanced telephone switch known as a Service Switching Point (SSP) allows advanced telephony services such as Advanced Intelligent Network (AIN) services to be provided on telephone calls that are received at the SSP. When a user of telephone 200 makes or receives a call, SSP 214 detects whether the user has advanced telephony services enabled, for example by reference to an advanced telephony service identifier associated with the user's telephone line such as an AIN trigger. An advanced telephony service identifier may include the advanced service user's telephone number. Once the SSP detects that the user is an advanced telephony services user, the SSP contacts a node 212 responsible for handling advanced telephony services in the network via STP 208. Node 212 may be a service platform such as a service control point (SCP) or application server which includes programmable data processing capabilities for control of one or more advanced telephony services. Provision of advanced telephony services may involve the SCP controlling an intelligent peripheral node 216 via a Primary Rate Interface (PRI) (or alternatively via an SS7 signaling connection) to provide advanced resources for the call, for example playing voice announcements, collecting DTMF tones from a user or other services. Some existing local telephone exchange switches do not provide the ability to generate at least some types of AIN queries that are triggered by incoming or outgoing calls.
United States patent application US-A-2004/0052350 describes a method whereby a service platform provider, separate from a local phone company, may provide advanced services, not provided by the local phone company, to customers of the local phone company. The customer, or the service platform provider, may purchase a call forwarding service from the local phone company and have phone calls, originally directed to a POTS line provided by the local phone company, forwarded to a service platform. This is used to provide the customer with advanced services according to a customer profile stored on the service platform, for example IP telephony. The service platform can also forward the phone call back to the original POTS line via a distinctive ring number which is different to the main telephone number of the customer. This enables a simultaneous ring service, allowing the customer to be contacted on a device associated with the service platform, for example, an IP telephone, as well as the POTS telephone, simultaneously, and allowing the customer to decide which telephone to answer. Since the service platform provider and the local phone company are different, the subscriber must deal with two different service providers and the services provided by each may have interworking difficulties.
In US-A-2004/0052350, a subscriber may be able to configure a service supported by their local exchange via an interface on their local exchange. The interface on the local exchange may require input of DTMF tones on a subscriber's telephone, whereas the service platform may require input on a different interface via a suitable computing device having network access. The subscriber may, due to lack of understanding of the interworking between the systems, configure the local exchange settings and the service platform settings in such a way that they conflict. For example, the subscriber may change the call forwarding number by which the call is forwarded the call to a service platform, thus unintentionally disabling the services provided by the service platform. Moreover, a setting for a service provided by the local exchange may interfere with a setting for a service provided by a service platform. This might involve settings on two different, unrelated services, or settings on related services which interact with each other in an unexpected and/or undesirable manner. It would therefore be desirable to provide techniques whereby a range of advanced telephony services can be delivered to customers connected to such legacy local telephone exchange switches, whilst reducing interworking difficulties between the services provided.